Adding upstream version 115.8.0esr.upstream/115.8.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 727 insertions, 0 deletions

diff --git a/third_party/rust/tabs/src/storage.rs b/third_party/rust/tabs/src/storage.rs
new file mode 100644
index 0000000000..eaccbc3446
--- /dev/null
+++ b/third_party/rust/tabs/src/storage.rs
@@ -0,0 +1,727 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// From https://searchfox.org/mozilla-central/rev/ea63a0888d406fae720cf24f4727d87569a8cab5/services/sync/modules/constants.js#75
+const URI_LENGTH_MAX: usize = 65536;
+// https://searchfox.org/mozilla-central/rev/ea63a0888d406fae720cf24f4727d87569a8cab5/services/sync/modules/engines/tabs.js#8
+const TAB_ENTRIES_LIMIT: usize = 5;
+
+use crate::error::*;
+use crate::schema;
+use crate::sync::record::TabsRecord;
+use crate::DeviceType;
+use rusqlite::{
+    types::{FromSql, ToSql},
+    Connection, OpenFlags,
+};
+use serde_derive::{Deserialize, Serialize};
+use sql_support::open_database::{self, open_database_with_flags};
+use sql_support::ConnExt;
+use std::cell::RefCell;
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+use sync15::{RemoteClient, ServerTimestamp};
+pub type TabsDeviceType = crate::DeviceType;
+pub type RemoteTabRecord = RemoteTab;
+
+pub(crate) const TABS_CLIENT_TTL: u32 = 15_552_000; // 180 days, same as CLIENTS_TTL
+const FAR_FUTURE: i64 = 4_102_405_200_000; // 2100/01/01
+const MAX_PAYLOAD_SIZE: usize = 512 * 1024; // Twice as big as desktop, still smaller than server max (2MB)
+const MAX_TITLE_CHAR_LENGTH: usize = 512; // We put an upper limit on title sizes for tabs to reduce memory
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct RemoteTab {
+    pub title: String,
+    pub url_history: Vec<String>,
+    pub icon: Option<String>,
+    pub last_used: i64, // In ms.
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct ClientRemoteTabs {
+    // The fxa_device_id of the client. *Should not* come from the id in the `clients` collection,
+    // because that may or may not be the fxa_device_id (currently, it will not be for desktop
+    // records.)
+    pub client_id: String,
+    pub client_name: String,
+    #[serde(
+        default = "devicetype_default_deser",
+        skip_serializing_if = "devicetype_is_unknown"
+    )]
+    pub device_type: DeviceType,
+    // serde default so we can read old rows that didn't persist this.
+    #[serde(default)]
+    pub last_modified: i64,
+    pub remote_tabs: Vec<RemoteTab>,
+}
+
+fn devicetype_default_deser() -> DeviceType {
+    // replace with `DeviceType::default_deser` once #4861 lands.
+    DeviceType::Unknown
+}
+
+// Unlike most other uses-cases, here we do allow serializing ::Unknown, but skip it.
+fn devicetype_is_unknown(val: &DeviceType) -> bool {
+    matches!(val, DeviceType::Unknown)
+}
+
+// Tabs has unique requirements for storage:
+// * The "local_tabs" exist only so we can sync them out. There's no facility to
+//   query "local tabs", so there's no need to store these persistently - ie, they
+//   are write-only.
+// * The "remote_tabs" exist purely for incoming items via sync - there's no facility
+//   to set them locally - they are read-only.
+// Note that this means a database is only actually needed after Sync fetches remote tabs,
+// and because sync users are in the minority, the use of a database here is purely
+// optional and created on demand. The implication here is that asking for the "remote tabs"
+// when no database exists is considered a normal situation and just implies no remote tabs exist.
+// (Note however we don't attempt to remove the database when no remote tabs exist, so having
+// no remote tabs in an existing DB is also a normal situation)
+pub struct TabsStorage {
+    local_tabs: RefCell<Option<Vec<RemoteTab>>>,
+    db_path: PathBuf,
+    db_connection: Option<Connection>,
+}
+
+impl TabsStorage {
+    pub fn new(db_path: impl AsRef<Path>) -> Self {
+        Self {
+            local_tabs: RefCell::default(),
+            db_path: db_path.as_ref().to_path_buf(),
+            db_connection: None,
+        }
+    }
+
+    /// Arrange for a new memory-based TabsStorage. As per other DB semantics, creating
+    /// this isn't enough to actually create the db!
+    pub fn new_with_mem_path(db_path: &str) -> Self {
+        let name = PathBuf::from(format!("file:{}?mode=memory&cache=shared", db_path));
+        Self::new(name)
+    }
+
+    /// If a DB file exists, open and return it.
+    pub fn open_if_exists(&mut self) -> Result<Option<&Connection>> {
+        if let Some(ref existing) = self.db_connection {
+            return Ok(Some(existing));
+        }
+        let flags = OpenFlags::SQLITE_OPEN_NO_MUTEX
+            | OpenFlags::SQLITE_OPEN_URI
+            | OpenFlags::SQLITE_OPEN_READ_WRITE;
+        match open_database_with_flags(
+            self.db_path.clone(),
+            flags,
+            &crate::schema::TabsMigrationLogic,
+        ) {
+            Ok(conn) => {
+                self.db_connection = Some(conn);
+                Ok(self.db_connection.as_ref())
+            }
+            Err(open_database::Error::SqlError(rusqlite::Error::SqliteFailure(code, _)))
+                if code.code == rusqlite::ErrorCode::CannotOpen =>
+            {
+                Ok(None)
+            }
+            Err(e) => Err(e.into()),
+        }
+    }
+
+    /// Open and return the DB, creating it if necessary.
+    pub fn open_or_create(&mut self) -> Result<&Connection> {
+        if let Some(ref existing) = self.db_connection {
+            return Ok(existing);
+        }
+        let flags = OpenFlags::SQLITE_OPEN_NO_MUTEX
+            | OpenFlags::SQLITE_OPEN_URI
+            | OpenFlags::SQLITE_OPEN_READ_WRITE
+            | OpenFlags::SQLITE_OPEN_CREATE;
+        let conn = open_database_with_flags(
+            self.db_path.clone(),
+            flags,
+            &crate::schema::TabsMigrationLogic,
+        )?;
+        self.db_connection = Some(conn);
+        Ok(self.db_connection.as_ref().unwrap())
+    }
+
+    pub fn update_local_state(&mut self, local_state: Vec<RemoteTab>) {
+        self.local_tabs.borrow_mut().replace(local_state);
+    }
+
+    // We try our best to fit as many tabs in a payload as possible, this includes
+    // limiting the url history entries, title character count and finally drop enough tabs
+    // until we have small enough payload that the server will accept
+    pub fn prepare_local_tabs_for_upload(&self) -> Option<Vec<RemoteTab>> {
+        if let Some(local_tabs) = self.local_tabs.borrow().as_ref() {
+            let mut sanitized_tabs: Vec<RemoteTab> = local_tabs
+                .iter()
+                .cloned()
+                .filter_map(|mut tab| {
+                    if tab.url_history.is_empty() || !is_url_syncable(&tab.url_history[0]) {
+                        return None;
+                    }
+                    let mut sanitized_history = Vec::with_capacity(TAB_ENTRIES_LIMIT);
+                    for url in tab.url_history {
+                        if sanitized_history.len() == TAB_ENTRIES_LIMIT {
+                            break;
+                        }
+                        if is_url_syncable(&url) {
+                            sanitized_history.push(url);
+                        }
+                    }
+
+                    tab.url_history = sanitized_history;
+                    // Potentially truncate the title to some limit
+                    tab.title = slice_up_to(tab.title, MAX_TITLE_CHAR_LENGTH);
+                    Some(tab)
+                })
+                .collect();
+            // Sort the tabs so when we trim tabs it's the oldest tabs
+            sanitized_tabs.sort_by(|a, b| b.last_used.cmp(&a.last_used));
+            // If trimming the tab length failed for some reason, just return the untrimmed tabs
+            trim_tabs_length(&mut sanitized_tabs, MAX_PAYLOAD_SIZE);
+            return Some(sanitized_tabs);
+        }
+        None
+    }
+
+    pub fn get_remote_tabs(&mut self) -> Option<Vec<ClientRemoteTabs>> {
+        let conn = match self.open_if_exists() {
+            Err(e) => {
+                error_support::report_error!(
+                    "tabs-read-remote",
+                    "Failed to read remote tabs: {}",
+                    e
+                );
+                return None;
+            }
+            Ok(None) => return None,
+            Ok(Some(conn)) => conn,
+        };
+
+        let records: Vec<(TabsRecord, ServerTimestamp)> = match conn.query_rows_and_then_cached(
+            "SELECT record, last_modified FROM tabs",
+            [],
+            |row| -> Result<_> {
+                Ok((
+                    serde_json::from_str(&row.get::<_, String>(0)?)?,
+                    ServerTimestamp(row.get::<_, i64>(1)?),
+                ))
+            },
+        ) {
+            Ok(records) => records,
+            Err(e) => {
+                error_support::report_error!("tabs-read-remote", "Failed to read database: {}", e);
+                return None;
+            }
+        };
+        let mut crts: Vec<ClientRemoteTabs> = Vec::new();
+        let remote_clients: HashMap<String, RemoteClient> =
+            match self.get_meta::<String>(schema::REMOTE_CLIENTS_KEY) {
+                Err(e) => {
+                    error_support::report_error!(
+                        "tabs-read-remote",
+                        "Failed to get remote clients: {}",
+                        e
+                    );
+                    return None;
+                }
+                // We don't return early here since we still store tabs even if we don't
+                // "know" about the client it's associated with (incase it becomes available later)
+                Ok(None) => HashMap::default(),
+                Ok(Some(json)) => serde_json::from_str(&json).unwrap(),
+            };
+        for (record, last_modified) in records {
+            let id = record.id.clone();
+            let crt = if let Some(remote_client) = remote_clients.get(&id) {
+                ClientRemoteTabs::from_record_with_remote_client(
+                    remote_client
+                        .fxa_device_id
+                        .as_ref()
+                        .unwrap_or(&id)
+                        .to_owned(),
+                    last_modified,
+                    remote_client,
+                    record,
+                )
+            } else {
+                // A record with a device that's not in our remote clients seems unlikely, but
+                // could happen - in most cases though, it will be due to a disconnected client -
+                // so we really should consider just dropping it? (Sadly though, it does seem
+                // possible it's actually a very recently connected client, so we keep it)
+                // We should get rid of this eventually - https://github.com/mozilla/application-services/issues/5199
+                log::info!(
+                    "Storing tabs from a client that doesn't appear in the devices list: {}",
+                    id,
+                );
+                ClientRemoteTabs::from_record(id, last_modified, record)
+            };
+            crts.push(crt);
+        }
+        Some(crts)
+    }
+
+    // Keep DB from growing infinitely since we only ask for records since our last sync
+    // and may or may not know about the client it's associated with -- but we could at some point
+    // and should start returning those tabs immediately. If that client hasn't been seen in 3 weeks,
+    // we remove it until it reconnects
+    pub fn remove_stale_clients(&mut self) -> Result<()> {
+        let last_sync = self.get_meta::<i64>(schema::LAST_SYNC_META_KEY)?;
+        if let Some(conn) = self.open_if_exists()? {
+            if let Some(last_sync) = last_sync {
+                let client_ttl_ms = (TABS_CLIENT_TTL as i64) * 1000;
+                // On desktop, a quick write temporarily sets the last_sync to FAR_FUTURE
+                // but if it doesn't set it back to the original (crash, etc) it
+                // means we'll most likely trash all our records (as it's more than any TTL we'd ever do)
+                // so we need to detect this for now until we have native quick write support
+                if last_sync - client_ttl_ms >= 0 && last_sync != (FAR_FUTURE * 1000) {
+                    let tx = conn.unchecked_transaction()?;
+                    let num_removed = tx.execute_cached(
+                        "DELETE FROM tabs WHERE last_modified <= :last_sync - :ttl",
+                        rusqlite::named_params! {
+                            ":last_sync": last_sync,
+                            ":ttl": client_ttl_ms,
+                        },
+                    )?;
+                    log::info!(
+                        "removed {} stale clients (threshold was {})",
+                        num_removed,
+                        last_sync - client_ttl_ms
+                    );
+                    tx.commit()?;
+                }
+            }
+        }
+        Ok(())
+    }
+}
+
+impl TabsStorage {
+    pub(crate) fn replace_remote_tabs(
+        &mut self,
+        // This is a tuple because we need to know what the server reports
+        // as the last time a record was modified
+        new_remote_tabs: Vec<(TabsRecord, ServerTimestamp)>,
+    ) -> Result<()> {
+        let connection = self.open_or_create()?;
+        let tx = connection.unchecked_transaction()?;
+
+        // For tabs it's fine if we override the existing tabs for a remote
+        // there can only ever be one record for each client
+        for remote_tab in new_remote_tabs {
+            let record = remote_tab.0;
+            let last_modified = remote_tab.1;
+            log::info!(
+                "inserting tab for device {}, last modified at {}",
+                record.id,
+                last_modified.as_millis()
+            );
+            tx.execute_cached(
+                "INSERT OR REPLACE INTO tabs (guid, record, last_modified) VALUES (:guid, :record, :last_modified);",
+                rusqlite::named_params! {
+                    ":guid": &record.id,
+                    ":record": serde_json::to_string(&record).expect("tabs don't fail to serialize"),
+                    ":last_modified": last_modified.as_millis()
+                },
+            )?;
+        }
+        tx.commit()?;
+        Ok(())
+    }
+
+    pub(crate) fn wipe_remote_tabs(&mut self) -> Result<()> {
+        if let Some(db) = self.open_if_exists()? {
+            db.execute_batch("DELETE FROM tabs")?;
+        }
+        Ok(())
+    }
+
+    pub(crate) fn wipe_local_tabs(&self) {
+        self.local_tabs.replace(None);
+    }
+
+    pub(crate) fn put_meta(&mut self, key: &str, value: &dyn ToSql) -> Result<()> {
+        let db = self.open_or_create()?;
+        db.execute_cached(
+            "REPLACE INTO moz_meta (key, value) VALUES (:key, :value)",
+            &[(":key", &key as &dyn ToSql), (":value", value)],
+        )?;
+        Ok(())
+    }
+
+    pub(crate) fn get_meta<T: FromSql>(&mut self, key: &str) -> Result<Option<T>> {
+        match self.open_if_exists() {
+            Ok(Some(db)) => {
+                let res = db.try_query_one(
+                    "SELECT value FROM moz_meta WHERE key = :key",
+                    &[(":key", &key)],
+                    true,
+                )?;
+                Ok(res)
+            }
+            Err(e) => Err(e),
+            Ok(None) => Ok(None),
+        }
+    }
+
+    pub(crate) fn delete_meta(&mut self, key: &str) -> Result<()> {
+        if let Some(db) = self.open_if_exists()? {
+            db.execute_cached("DELETE FROM moz_meta WHERE key = :key", &[(":key", &key)])?;
+        }
+        Ok(())
+    }
+}
+
+// Trim the amount of tabs in a list to fit the specified memory size
+fn trim_tabs_length(tabs: &mut Vec<RemoteTab>, payload_size_max_bytes: usize) {
+    // Ported from https://searchfox.org/mozilla-central/rev/84fb1c4511312a0b9187f647d90059e3a6dd27f8/services/sync/modules/util.sys.mjs#422
+    // See bug 535326 comment 8 for an explanation of the estimation
+    let max_serialized_size = (payload_size_max_bytes / 4) * 3 - 1500;
+    let size = compute_serialized_size(tabs);
+    if size > max_serialized_size {
+        // Estimate a little more than the direct fraction to maximize packing
+        let cutoff = (tabs.len() * max_serialized_size) / size;
+        tabs.truncate(cutoff);
+
+        // Keep dropping off the last entry until the data fits.
+        while compute_serialized_size(tabs) > max_serialized_size {
+            tabs.pop();
+        }
+    }
+}
+
+fn compute_serialized_size(v: &Vec<RemoteTab>) -> usize {
+    serde_json::to_string(v).unwrap_or_default().len()
+}
+
+// Similar to places/utils.js
+// This method ensures we safely truncate a string up to a certain max_len while
+// respecting char bounds to prevent rust panics. If we do end up truncating, we
+// append an ellipsis to the string
+pub fn slice_up_to(s: String, max_len: usize) -> String {
+    if max_len >= s.len() {
+        return s;
+    }
+
+    let ellipsis = '\u{2026}';
+    // Ensure we leave space for the ellipsis while still being under the max
+    let mut idx = max_len - ellipsis.len_utf8();
+    while !s.is_char_boundary(idx) {
+        idx -= 1;
+    }
+    let mut new_str = s[..idx].to_string();
+    new_str.push(ellipsis);
+    new_str
+}
+
+// Try to keep in sync with https://searchfox.org/mozilla-central/rev/2ad13433da20a0749e1e9a10ec0ab49b987c2c8e/modules/libpref/init/all.js#3927
+fn is_url_syncable(url: &str) -> bool {
+    url.len() <= URI_LENGTH_MAX
+        && !(url.starts_with("about:")
+            || url.starts_with("resource:")
+            || url.starts_with("chrome:")
+            || url.starts_with("wyciwyg:")
+            || url.starts_with("blob:")
+            || url.starts_with("file:")
+            || url.starts_with("moz-extension:")
+            || url.starts_with("data:"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::sync::record::TabsRecordTab;
+
+    #[test]
+    fn test_is_url_syncable() {
+        assert!(is_url_syncable("https://bobo.com"));
+        assert!(is_url_syncable("ftp://bobo.com"));
+        assert!(!is_url_syncable("about:blank"));
+        // XXX - this smells wrong - we should insist on a valid complete URL?
+        assert!(is_url_syncable("aboutbobo.com"));
+        assert!(!is_url_syncable("file:///Users/eoger/bobo"));
+    }
+
+    #[test]
+    fn test_open_if_exists_no_file() {
+        let dir = tempfile::tempdir().unwrap();
+        let db_name = dir.path().join("test_open_for_read_no_file.db");
+        let mut storage = TabsStorage::new(db_name.clone());
+        assert!(storage.open_if_exists().unwrap().is_none());
+        storage.open_or_create().unwrap(); // will have created it.
+                                           // make a new storage, but leave the file alone.
+        let mut storage = TabsStorage::new(db_name);
+        // db file exists, so opening for read should open it.
+        assert!(storage.open_if_exists().unwrap().is_some());
+    }
+
+    #[test]
+    fn test_tabs_meta() {
+        let dir = tempfile::tempdir().unwrap();
+        let db_name = dir.path().join("test_tabs_meta.db");
+        let mut db = TabsStorage::new(db_name);
+        let test_key = "TEST KEY A";
+        let test_value = "TEST VALUE A";
+        let test_key2 = "TEST KEY B";
+        let test_value2 = "TEST VALUE B";
+
+        // should automatically make the DB if one doesn't exist
+        db.put_meta(test_key, &test_value).unwrap();
+        db.put_meta(test_key2, &test_value2).unwrap();
+
+        let retrieved_value: String = db.get_meta(test_key).unwrap().expect("test value");
+        let retrieved_value2: String = db.get_meta(test_key2).unwrap().expect("test value 2");
+
+        assert_eq!(retrieved_value, test_value);
+        assert_eq!(retrieved_value2, test_value2);
+
+        // check that the value of an existing key can be updated
+        let test_value3 = "TEST VALUE C";
+        db.put_meta(test_key, &test_value3).unwrap();
+
+        let retrieved_value3: String = db.get_meta(test_key).unwrap().expect("test value 3");
+
+        assert_eq!(retrieved_value3, test_value3);
+
+        // check that a deleted key is not retrieved
+        db.delete_meta(test_key).unwrap();
+        let retrieved_value4: Option<String> = db.get_meta(test_key).unwrap();
+        assert!(retrieved_value4.is_none());
+    }
+
+    #[test]
+    fn test_prepare_local_tabs_for_upload() {
+        let mut storage = TabsStorage::new_with_mem_path("test_prepare_local_tabs_for_upload");
+        assert_eq!(storage.prepare_local_tabs_for_upload(), None);
+        storage.update_local_state(vec![
+            RemoteTab {
+                title: "".to_owned(),
+                url_history: vec!["about:blank".to_owned(), "https://foo.bar".to_owned()],
+                icon: None,
+                last_used: 0,
+            },
+            RemoteTab {
+                title: "".to_owned(),
+                url_history: vec![
+                    "https://foo.bar".to_owned(),
+                    "about:blank".to_owned(),
+                    "about:blank".to_owned(),
+                    "about:blank".to_owned(),
+                    "about:blank".to_owned(),
+                    "about:blank".to_owned(),
+                    "about:blank".to_owned(),
+                    "about:blank".to_owned(),
+                ],
+                icon: None,
+                last_used: 0,
+            },
+            RemoteTab {
+                title: "".to_owned(),
+                url_history: vec![
+                    "https://foo.bar".to_owned(),
+                    "about:blank".to_owned(),
+                    "https://foo2.bar".to_owned(),
+                    "https://foo3.bar".to_owned(),
+                    "https://foo4.bar".to_owned(),
+                    "https://foo5.bar".to_owned(),
+                    "https://foo6.bar".to_owned(),
+                ],
+                icon: None,
+                last_used: 0,
+            },
+            RemoteTab {
+                title: "".to_owned(),
+                url_history: vec![],
+                icon: None,
+                last_used: 0,
+            },
+        ]);
+        assert_eq!(
+            storage.prepare_local_tabs_for_upload(),
+            Some(vec![
+                RemoteTab {
+                    title: "".to_owned(),
+                    url_history: vec!["https://foo.bar".to_owned()],
+                    icon: None,
+                    last_used: 0,
+                },
+                RemoteTab {
+                    title: "".to_owned(),
+                    url_history: vec![
+                        "https://foo.bar".to_owned(),
+                        "https://foo2.bar".to_owned(),
+                        "https://foo3.bar".to_owned(),
+                        "https://foo4.bar".to_owned(),
+                        "https://foo5.bar".to_owned()
+                    ],
+                    icon: None,
+                    last_used: 0,
+                },
+            ])
+        );
+    }
+    #[test]
+    fn test_trimming_tab_title() {
+        let mut storage = TabsStorage::new_with_mem_path("test_prepare_local_tabs_for_upload");
+        assert_eq!(storage.prepare_local_tabs_for_upload(), None);
+        storage.update_local_state(vec![RemoteTab {
+            title: "a".repeat(MAX_TITLE_CHAR_LENGTH + 10), // Fill a string more than max
+            url_history: vec!["https://foo.bar".to_owned()],
+            icon: None,
+            last_used: 0,
+        }]);
+        let ellipsis_char = '\u{2026}';
+        let mut truncated_title = "a".repeat(MAX_TITLE_CHAR_LENGTH - ellipsis_char.len_utf8());
+        truncated_title.push(ellipsis_char);
+        assert_eq!(
+            storage.prepare_local_tabs_for_upload(),
+            Some(vec![
+                // title trimmed to 50 characters
+                RemoteTab {
+                    title: truncated_title, // title was trimmed to only max char length
+                    url_history: vec!["https://foo.bar".to_owned()],
+                    icon: None,
+                    last_used: 0,
+                },
+            ])
+        );
+    }
+    #[test]
+    fn test_utf8_safe_title_trim() {
+        let mut storage = TabsStorage::new_with_mem_path("test_prepare_local_tabs_for_upload");
+        assert_eq!(storage.prepare_local_tabs_for_upload(), None);
+        storage.update_local_state(vec![
+            RemoteTab {
+                title: "😍".repeat(MAX_TITLE_CHAR_LENGTH + 10), // Fill a string more than max
+                url_history: vec!["https://foo.bar".to_owned()],
+                icon: None,
+                last_used: 0,
+            },
+            RemoteTab {
+                title: "を".repeat(MAX_TITLE_CHAR_LENGTH + 5), // Fill a string more than max
+                url_history: vec!["https://foo_jp.bar".to_owned()],
+                icon: None,
+                last_used: 0,
+            },
+        ]);
+        let ellipsis_char = '\u{2026}';
+        // (MAX_TITLE_CHAR_LENGTH - ellipsis / "😍" bytes)
+        let mut truncated_title = "😍".repeat(127);
+        // (MAX_TITLE_CHAR_LENGTH - ellipsis / "を" bytes)
+        let mut truncated_jp_title = "を".repeat(169);
+        truncated_title.push(ellipsis_char);
+        truncated_jp_title.push(ellipsis_char);
+        let remote_tabs = storage.prepare_local_tabs_for_upload().unwrap();
+        assert_eq!(
+            remote_tabs,
+            vec![
+                RemoteTab {
+                    title: truncated_title, // title was trimmed to only max char length
+                    url_history: vec!["https://foo.bar".to_owned()],
+                    icon: None,
+                    last_used: 0,
+                },
+                RemoteTab {
+                    title: truncated_jp_title, // title was trimmed to only max char length
+                    url_history: vec!["https://foo_jp.bar".to_owned()],
+                    icon: None,
+                    last_used: 0,
+                },
+            ]
+        );
+        // We should be less than max
+        assert!(remote_tabs[0].title.chars().count() <= MAX_TITLE_CHAR_LENGTH);
+        assert!(remote_tabs[1].title.chars().count() <= MAX_TITLE_CHAR_LENGTH);
+    }
+    #[test]
+    fn test_trim_tabs_length() {
+        let mut storage = TabsStorage::new_with_mem_path("test_prepare_local_tabs_for_upload");
+        assert_eq!(storage.prepare_local_tabs_for_upload(), None);
+        let mut too_many_tabs: Vec<RemoteTab> = Vec::new();
+        for n in 1..5000 {
+            too_many_tabs.push(RemoteTab {
+                title: "aaaa aaaa aaaa aaaa aaaa aaaa aaaa aaaa aaaa aaaa" //50 characters
+                    .to_owned(),
+                url_history: vec![format!("https://foo{}.bar", n)],
+                icon: None,
+                last_used: 0,
+            });
+        }
+        let tabs_mem_size = compute_serialized_size(&too_many_tabs);
+        // ensure we are definitely over the payload limit
+        assert!(tabs_mem_size > MAX_PAYLOAD_SIZE);
+        // Add our over-the-limit tabs to the local state
+        storage.update_local_state(too_many_tabs.clone());
+        // prepare_local_tabs_for_upload did the trimming we needed to get under payload size
+        let tabs_to_upload = &storage.prepare_local_tabs_for_upload().unwrap();
+        assert!(compute_serialized_size(tabs_to_upload) <= MAX_PAYLOAD_SIZE);
+    }
+    // Helper struct to model what's stored in the DB
+    struct TabsSQLRecord {
+        guid: String,
+        record: TabsRecord,
+        last_modified: i64,
+    }
+    #[test]
+    fn test_remove_stale_clients() {
+        let dir = tempfile::tempdir().unwrap();
+        let db_name = dir.path().join("test_remove_stale_clients.db");
+        let mut storage = TabsStorage::new(db_name);
+        storage.open_or_create().unwrap();
+        assert!(storage.open_if_exists().unwrap().is_some());
+
+        let records = vec![
+            TabsSQLRecord {
+                guid: "device-1".to_string(),
+                record: TabsRecord {
+                    id: "device-1".to_string(),
+                    client_name: "Device #1".to_string(),
+                    tabs: vec![TabsRecordTab {
+                        title: "the title".to_string(),
+                        url_history: vec!["https://mozilla.org/".to_string()],
+                        icon: Some("https://mozilla.org/icon".to_string()),
+                        last_used: 1643764207000,
+                    }],
+                },
+                last_modified: 1643764207000,
+            },
+            TabsSQLRecord {
+                guid: "device-outdated".to_string(),
+                record: TabsRecord {
+                    id: "device-outdated".to_string(),
+                    client_name: "Device outdated".to_string(),
+                    tabs: vec![TabsRecordTab {
+                        title: "the title".to_string(),
+                        url_history: vec!["https://mozilla.org/".to_string()],
+                        icon: Some("https://mozilla.org/icon".to_string()),
+                        last_used: 1643764207000,
+                    }],
+                },
+                last_modified: 1443764207000, // old
+            },
+        ];
+        let db = storage.open_if_exists().unwrap().unwrap();
+        for record in records {
+            db.execute(
+                "INSERT INTO tabs (guid, record, last_modified) VALUES (:guid, :record, :last_modified);",
+                rusqlite::named_params! {
+                    ":guid": &record.guid,
+                    ":record": serde_json::to_string(&record.record).unwrap(),
+                    ":last_modified": &record.last_modified,
+                },
+            ).unwrap();
+        }
+        // pretend we just synced
+        let last_synced = 1643764207000_i64;
+        storage
+            .put_meta(schema::LAST_SYNC_META_KEY, &last_synced)
+            .unwrap();
+        storage.remove_stale_clients().unwrap();
+
+        let remote_tabs = storage.get_remote_tabs().unwrap();
+        // We should've removed the outdated device
+        assert_eq!(remote_tabs.len(), 1);
+        // Assert the correct record is still being returned
+        assert_eq!(remote_tabs[0].client_id, "device-1");
+    }
+}